If you search disease, you'll see pictures of unhealthy foliage.
I suspect that your plant is otherwise healthy, and non-flowering is environmental.... same as here...
I have some peonies in town that bloomed beautifully 3 years ago... and nothing since... and before that year of bloom?
Nothing much... Plants have been in same spot for 20+ years...
https://www.walterreeves.com/l...